1908] 



POND—SOLUTION TENSION AND TOXICITY 



242 



conccntration.s except m/i()T,'^^. The amount of the precipitate varies 

 directly with the concentration of the reagent. 



TABLE X: Copper and lead in contemporaneous test 



LEAD 



16384 

 8192 

 4096 

 2048 

 1024 



Enzyme 0.05 per cent. Incubation 5 hours at 40 C. 



All the vials except the w/ 16384 contained .sediment at the close 

 of incubation. The figures for copper are practically a duplicate of 

 those in Table IX. Lead seems to be not quite so toxic as copper in 



TABLE XI: Copper, lead, and zinc in contemporaneous test 



COPPER 



LEAD 



4096. 



2048. 



1024. 



512. 



O. 22 

 0.28 

 0.40 

 0.50 



0.06 

 0.04 

 0.00 

 0.00 



ZINC 



4096 . 



2048. 



1024. 



512. 



o. 10 

 o. 20 

 0.40 



0.85 



o. 23 

 0.30 

 0.50 



0.85 



0.05 



0.04 

 0.00 

 0.00 



Enzyme 0.05 per cent. Incubation 5 hours at 40° C 



